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CryptoHack

A fun, free platform for learning modern cryptography

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Learn By Doing

Learn about modern cryptography by solving a series of interactive puzzles and challenges. Get to know the ciphers and protocols that secure the digital world by breaking them.

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Level Up

Earn points by solving challenges. Finish categories to earn trophies and gain levels to track your progress. Can you reach the top of the scoreboard?

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Fresh Challenges

We are constantly creating new challenges to keep your crypto knowledge up to date. Expect exciting brainteasers and whole new categories as the site continues to grow.

New Challenges
Blind (ECSC 2023 (Norway)) CTF Archive 0
WOTS Up (ECSC 2023 (Norway)) CTF Archive 0
Irish flan (ECSC 2023 (Norway)) CTF Archive 0
WOTS Up 2 (ECSC 2023 (Norway)) CTF Archive 0
Twist and shout (ECSC 2023 (Norway)) CTF Archive 0
Weekly Top Users
#1 sceleri 4020
#2 F0DH1L 2145
#3 mathysEthical 1910
#4 Glacialte 1635
#5 MadRat_0 1470
Recent Solves
Bytes and Big Integers sage
Bespoke Padding Sinhro
RSA Starter 3 adrian_z
Background Reading Sinhro
RSA Starter 4 Toll
Recent Solutions
Successive Powers nk0 0
Lazy CBC nk0 0
Flipping Cookie nk0 0
Greatest Common Divisor Psi505 0
Extended GCD yasser_rafid 0

Level Up

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